The Sahel that extends from the Atlantic Ocean to the Ethiopian highland is a historical reservoir of Africa’s cultures and grandest populations and a known arena of ancient and recent migrations. We are interested in the issue whether such migrations were also carriers of genetic traits and whether this introgression could be associated with population genetic markers. Based on analysis of Y-chromosome haplogroups, we present evidence that the sickle gene, one of the major protective polymorphisms known in malaria, has in fact found its way only recently to the gene pool of the populations in eastern Sahel. We discuss the possible dynamics of the process and give estimates of the age of the introduction of the S allele into eastern Sahel.
The association of the P25 with the S gene in Hausa, which barely holds (P=0.07) in spite of the relatively large effective population size of the Hausa (Hassan et al, unpublished), might indicate that the S mutation may have been affiliated with a male founder belonging to Y haplogroup R1b-P25. The observed frequency among S-gene carriers in populations other than Hausa makes a strong case for gene flow from the Hausa to local groups in Sudan.
Busy chasing down the p25 Y chromosome today. This study does suggest to me that the R1b may have got into Cameroon in very low amounts originally but SC trait might have got into a small group carrying mainly R1b1 and this turbo boosted a founder effect on it. The Hausa appeaer to be vectors of the SC trait and p25 into East Africa, with a fairly recent Eastward movement (about 300 years old).